Objective To investigate the direct effect of leptin on osteoblast-like cell line MG63. Methods Human osteoblast-like cell line MG63 was incubated with leptin of different doses for 24, 48 and 72 h, respectively. The proliferation of MG63 was determined by methylene blue assay. Alpha1 (I) collagen gene expression in MG63 was determined by real time flourescence quantitive PCR (FQ-PCR), both with 17β-E_ 2 as positive control. Results Leptin accelerated the proliferation and differentiation of MG63 in dose and time-dependent manners, with the best effect at 10 -7 mol/L at 72 h. Compared with 17β-E_ 2 , leptin showed a weaker promoting effect at all of the three time point: 24, 48 and 72 h. While the effects of the two hormones have an approaching trend the time prolonged. Conclusion Leptin has the effects of accelerating the proliferation and differentiation of MG63 cells in vitro, which is more enduring and later than that of 17β-E_2 . Objective To investigate the direct effect of leptin on osteoblast-like cell line MG63. Methods Human osteoblast-like cell line MG63 was incubated with leptin of different doses for 24, 48 and 72 h, respectively. The proliferation of MG63 was determined by methylene blue Alpha1 (I) collagen gene expression in MG63 was determined by real time flourescence quantitive PCR (FQ-PCR), both with 17β-E_2 as positive control. Results Leptin accelerated the proliferation and differentiation of MG63 in dose and time-dependent manners, with the best effect at 10 -7 mol / L at 72 h. Compared with 17β-E_ 2, leptin showed a weaker promoting effect at all of the three time points: 24, 48 and 72 h. While the effects of the Two hormones have an approaching trend of time prolonged. Conclusion Leptin has the effects of accelerating the proliferation and differentiation of MG63 cells in vitro, which is more enduring and later than that of 17β-E_2.